As disclosed in Kirk-Othmer, Encyclopedia of Chemical Third Edition, Volume 2, pp. 259-271, it is known that amine oxides which are useful in various applications, such as detergent and shampoo formulations, can be prepared by reacting non-heterocyclic tert-amines with aqueous hydrogen peroxide in a solvent such as water, a lower alcohol, acetone, or acetic acid.
Copending application Ser. No. 415,910 (Smith et al. ), filed Oct. 2, 1989, teaches that it is also possible to prepare the amine oxides as solid, non-hygroscopic dihydrates by conducting their syntheses in organic solvents, such as esters, hydrocarbons, and highly polar solvents, in which the products are soluble at reaction temperatures but insoluble at a lower temperature.
These amine oxides, which are generally trialkylamine oxides, particularly trialkylamine oxides containing both short and long alkyl groups, are sometimes utilizable as prepared. However, the solid amine oxides present handling problems; and the solvents used in the known syntheses of amine oxides, especially the flammable solvents and water, are apt to be undesirable in some applications. Moreover, even when not undesirable because of making a harmful contribution, such as an excess of water in a water-sensitive formulation, the solvents have the unattractive feature of contributing weight and bulk to amine oxide-containing formulations without serving a useful purpose therein.
It would be advantageous to be able to provide amine oxide compositions which could be poured or pumped from the vessels in which they are prepared to combine them with other ingredients of formulations in which they are to be incorporated, e.g., water-sensitive formulations, without having them in conjunction with solvents that would serve no useful function in the formulations and could be deleterious.
U.S. Pat. No. 3,565,810 (Mausner et al.) shows a recognition of some of these problems and an attempt to solve them, but its process uses so much water that its products have too much unnecessary bulk and weight and would not be suitable for incorporation into water-sensitive formulations.